The genome of the obligate endobacterium of an AM fungus reveals an interphylum network of nutritional interactions
The genome of the obligate endobacterium of an AM fungus reveals an interphylum network of nutritional interactions
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DOI：
10.1038/ismej.2011.110
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发表时间：
2012-01-01
期刊：
影响因子：
11
通讯作者：
Bonfante, Paola
中科院分区：
文献类型：
--
作者：
Ghignone, Stefano;Salvioli, Alessandra;Bonfante, Paola
丛枝菌根真菌（AMF）作为大多数陆地植物的专性共生体，在生态系统中具有重要作用，但迄今为止，在缺乏基因组数据的情况下，其适应生物学仍然难以捉摸。此外，在其细胞质中发现了内细菌，其作用尚不清楚。为了研究AMF Gigaspora margarita的一种内生细菌，革兰氏阴性芽孢杆菌Glomeribacter gigasporarum的功能，我们对其基因组进行了测序，导致类似于1.72-Mb的组装。系统发育分析将Ca。G. gigasporarum在伯克霍尔德氏菌科，而代谢网络分析聚类它与昆虫内细菌。这是Ca的定位。G. gigasporarum在不同细菌纲中的进化表明，它经历了趋同进化，以适应细胞内的生活方式。这种菌根真菌内生细菌的基因组注释揭示了一种意想不到的遗传镶嵌，其中共生、致病和自由生活的细菌的典型决定因素整合在简化的基因组中。约G. gigasporarum是一种需氧微生物，依赖其宿主提供碳，磷和氮;它还表达II型和III型分泌系统，并合成维生素B12，抗寄生虫和毒素分子，这可能有助于真菌宿主的生态适应性。约G.巨孢霉对其宿主的营养和能量具有极端的依赖性，而真菌宿主本身是依赖于光合植物的专性生物营养体。我们的工作代表了解开复杂的门间相互作用网络的第一步，预计这将产生以前未被认识到的生态影响。The ISME Journal（2012）6，136-145; doi：10.1038/ismej.2011.110; 2011年8月25日在线发表
As obligate symbionts of most land plants, arbuscular mycorrhizal fungi (AMF) have a crucial role in ecosystems, but to date, in the absence of genomic data, their adaptive biology remains elusive. In addition, endobacteria are found in their cytoplasm, the role of which is unknown. In order to investigate the function of the Gram-negative Candidatus Glomeribacter gigasporarum, an endobacterium of the AMF Gigaspora margarita, we sequenced its genome, leading to an similar to 1.72-Mb assembly. Phylogenetic analyses placed Ca. G. gigasporarum in the Burkholderiaceae whereas metabolic network analyses clustered it with insect endobacteria. This positioning of Ca. G. gigasporarum among different bacterial classes reveals that it has undergone convergent evolution to adapt itself to intracellular lifestyle. The genome annotation of this mycorrhizal-fungal endobacterium has revealed an unexpected genetic mosaic where typical determinants of symbiotic, pathogenic and free-living bacteria are integrated in a reduced genome. Ca. G. gigasporarum is an aerobic microbe that depends on its host for carbon, phosphorus and nitrogen supply; it also expresses type II and type III secretion systems and synthesizes vitamin B12, antibiotics-and toxin-resistance molecules, which may contribute to the fungal host's ecological fitness. Ca. G. gigasporarum has an extreme dependence on its host for nutrients and energy, whereas the fungal host is itself an obligate biotroph that relies on a photosynthetic plant. Our work represents the first step towards unraveling a complex network of interphylum interactions, which is expected to have a previously unrecognized ecological impact. The ISME Journal (2012) 6, 136-145; doi:10.1038/ismej.2011.110; published online 25 August 2011